Apparatus for forming external threads in a workpiece



Feb. 13, 1940. G H HAGERMAN 2,189,868

APPARATUS FOR FORMING EXTERNAL THREADS IN A WORKPIECE Feb. 13, 1949.. H HAGERMAN V2,189,868

APPARATUS FOR FORMING EXTERNAL THREADS IN A WORKPIECE .n gk ,n Filed Oct. 8, l958 v4 Sheets-Shee-t 2 3 noentor Mld/l1,

Gttornegld Feb. 13, 1940. G. H. HAGERMAN 2,189,868

APPARATUS FOR FORMING EXTERNAL THREADS IN A WORKPIECE Filed oct'. 8, 193s 4 sheets-sheet s vl and l Gttornegs Feb. 13, 1940. G. H. HAGERMAN APPARATUS FOR FORMING EXTERNAL rflilDS IN A WORKPIECE.

Filed Ob. 8, 1938 4 Sheets-Sheet 4 Wal Cttorneg Patented Feb. 13, 1940 N UNITED STATES APPARATUS FOR FORIVIING EXTERNAL THREADS IN A `VVORKPIECE Gilbert H. Hagerman, Dayton, Ohio, assignor, by t mesne assignments, to Societe dExploitation des Brevets Moine'au, Luxembourg, Luxembourg Application October 8,

, 2 Claims.

This invention relates to an apparatus for manufacturing one of the two helical members employed in the gear mechanism described in United States Letters Patent No. 1,892,217, dated December 27, `i932, to R. J. L. Moineau, and United States Letters Patent No. 2,028,407, dated January 2l, 1936, to the same inventor, the particular helical member for which this invention is adapted being what will be hereafter termed the rotor as distinguished from the stator, and on which thev helical threads are turned on theA exterior surface thereof. n Y

In those' two United States patents there is described a gear mechanism particularly adapted for pumps for fluids, consisting of two helical members disposed one within the other and, as before stated, this invention relates to a method and mechanism Vfor carrying out the method such as a lathe for `turning the rotary element of the two helical members.

One of the objects of the invention is to provide an apparatus for forming a helical rotor of the character described which will be simple in construction, economical in manufacture, and effective for the purpose for which` it is designed.

A further and more specific object is to provide a mechanism in the form of a lathe which will provide for rotating the workpiece, Which in the present case is the rotor referred to, upon its own axis,y and also provide for moving the axis of the'workpiece in a circular direction with relation to the cutting tool, so that the circular path will intersect the cutting point of the tool, this circular path being imparted to the axis of f the workpiece by eccentric devices, the movement of the cutting tool being a uniform feeding movement in the direction of the length of the workpiece.

A furtherv and more specific object of the invention is` to provide a mechanism whereby a predetermined number of revolutions of the workpiece on its own axis will be imparted thereto with relationtothe feed of the cutting tool corresponding to one pitch distance of the final helical form of 'the workpiece and also a predetermined number of circular movements of the axis of the workpiece imparted thereto during the same movement of the cutting tool; the movements which are imparted to the workpiece and vits airis being so proportioned by means 'y of suitable gearing and the feeding movement of the cutting tool being such that the desired helical shapeto the workpiece will be applied thereto.

A further object of the invention is to pro- 1938, Serial No. 233,994

vide an apparatus for forming spiral threads on the workpiece in which a cutter movable in the direction of the axis of the workpiece is employed, consisting in providing an arrangementv whereby the workpiece is brought into eiective cut- 5 ting relation with the cutter on a helical line extending but once about the workpiece during a given distance of travel of the cutter. l

In the accompanying drawings: .i

Fig. 1 is a top plan View of an apparatus in the l0 form of a lathe which is` employed for carrying out the invention. l

Fig. 2 is a side elevation of the forward side l of the machine or that side upon which the operator stands.` i

Fig. 3 is an elevation of the side of the machine.

Fig. 4 is an enlarged top plan View of ysome ,of the parts shown in Fig. 1.

. 15 opposite or rear Fig. 5 is an enlarged end elevation partly broken away and shown in section of the `tail stock.

Fig. 6 is an end elevation of the machine look-, ing from the left in Fig. 2.

Fig. .'7 is a detail sectional view on `theline 1-1 of Fig. 4, showing the parts in one position of operation.

Fig. 8 is also a section on the line 'I-'I of Fig.y 4, showing the parts in a different position of operation. Fig. 9 is also a section on the line '1 -'l of Fig. 4, showing the parts in `another different posi-` tion of operation.

Fig. 10 is an end elevation of a portion of one of the universal driving mechanisms for the 35"` mandrel which supports the work-piece.

Fig. 11 is an elevation of one of the mandrels which support the workpiece.

Fig. i2 is a view of one end thereof. i

Fig. 13 is an end view of the other end thereof. 40

Fig. 14 is a side elevation of one of the eccentric centers for the mandrel.

Fig. l5 is an end view of one end of the same.

Fig. 16 is a view of theother end of the same.

In forming the workpiece there imparted thereto arcta-ry movement` upon its own axis with relation to the cutting tool and aiso a movement in a circular path with relation to the cutting tool, resulting in the workpiece beingpresented to 50 to the action of the cutter on a helical line extending but once about the workpiece for a pre#` determined distance of movement of the cutter, this line being a helical one. The means for imparting the rrotary `movement to the workpieceg;`

. upon its own axis will be first described as follows:

All of the parts are supported upon a suitable `base indicated at I. The workpiece which is indicated at 2 is mounted upon a pair of mandrels indicated at 3 and 4, one of these mandrels which is the tail stock mandrel being shown in detail in Figs. 11, 12 and 13. The stem of each one of these mandrels is inserted in a longitudinal bore in the workpiece 2 as shown in dotted lines in Figs. 1, 2 and e, and each has a head 4 provided with a conical depression 4 together with a keyway 4".

The machine, which is a lathe, has in the usual way a head stock and a tail stock, the mechanisms of which are substantially alike so that the description will be conned mostly to but one of these stocks, the one shown and described in detail being the tail stock. The head stock is shown in a general way at H and the tail stock shown 4in a general way at T.

The conical recess of each mandrel receives the conical `pin 5 which is carried by a disk 6, the point being formed on a plug 5 which is pressed with a tight t in the disk Ii, and is eccentrically positioned therein, this plug having a flange 'I concentric with the point 5 for a purpose to be described. The disk 6 also has a boss 8 'which is inserted in an opening 9 in an extended portion ID of a gear II, the disk being provided with suitable openings I2 to receive bolts I3 which are screwed into openings I4 in. the extended portion Ill of the gear II. The connection of each disk 6 of the respective stocks which carry the points 5 with the respective gears Il will be hereinafter more specifically referred to in connection with the description of the means for imparting a movement of the workpiece in a v.circular direction with respect to the cutting tool.

Each of the mandrel heads has been described as having a keyway 4"'. When each mandrel is positioned upon one of the points 5 it is inserted through an opening I5 in a block IB which has a rkey I'I which enters the keyway 4"' so as to connect the mandrel with said block. This block has a pair of oppositely extending trunnions I8 which are slidably mounted in apertures in a ring I9 which in turn has oppositely extending trunnions 20 which project at right-angles to the trunnionsl and are slidably mounted in bearing caps 2l which are bolted to a gear 22 by bolts 23 which are screwed into openings 24 in the gear.

The gear 22 is rotated from gear 25 through the idler gear 26 (Figs. 1, 3, 4 and 5), said gear being driven by a shaft 21, the gear being keyed to the shaft so as to be longitudinally movable thereon for a purpose to be explained later. The shaft 21 is connected with a gear 2B in the head stock H and the gear 28 is driven from a gear II through an idler 3l), the gear II' being connected with a power spindle 3| having a cone pulley 32 to which power is applied from any suitable source through a belt (not shown), four of these pulleys being shown in the present case', whereby a change of speed of the mechanism may be effected.

y a gear 34 fast to a tubular shaft 35, a gear 35 fast to the shaft 35 and a gear 3l which is adapted to be thrown into or out of driving relation with the spindle by clutch mechanism which is not shown as it is common in change of speed mechanism of this character.

By the construction so far described it will be seen that each mandrel which carries the workpiece will be rotated upon its own axis, so that the workpiece will be likewise rotated.

It has been heretofore stated that in addition to rotating the workpiece upon its own axis an eccentric movement is imparted to the axis thereof with relation to the cutter, this eccentric movement being in a circular path in a vertical plane at rightangles to the axis of the workpiece. It has been heretofore explained that each mandrel is connected with a block I6 which has a universal movement. As shown best in Figs. '7. 8 and 9 the flange l which is carried by the plug 5 projects into the opening I5 in the block I5 just behind the key I l. As shown best in Figs. l5 and 16 this flange is eccentrically arranged with respect to the disk E so that as the ilange is rotated from the gear II, an eccentric movement in a circular path will be imparted to the block Id and hence to the mandrel connected therewith and to the workpiece. The gear I I in the tail stock is driven from the gear 25 through the medium of a gear 38 and idler 39, the gear II being connected with a shaft EI which is rotatably mounted in a sleeve I I extending from the slide 6I). While the corresponding gear II of the head stock is' rotated as before stated through its connection with the spindle 3|, the ratio of gearing being such, of course, that these gears II and II rotate at the same speed.

The cutting tool is indicated at 40, this being an ordinary sharp-pointed lathe tool. The tool head 4I is adjustably mounted upon a carriage 42 and has the usual adjusting means whereby the tool may be adjusted to or from the circular path of movement of the axis of the workpiece. The carriage 42 is mounted upon a way 43 on the base I and provision is made for imparting to the carriage a uniform or timed movement in a direction parallel with the axis of the workpiece through the medium of a lead screw 44 which is rotated as follows: Connected with the lead screw at the left-hand end of the machine is viewed in Figs. 1. 2 and 6 is a gear 45 which meshes with a pinion LSG which is connected with a gear 47, the pinion and gear being rotatably mounted upon a stub shaft 48. The gear 4'! meshes with a pinion 49 which is connected with a gear 5D, the pinion and gear being loosely journalled upon a short shaft 5I which is carried by an adjustable bracket 52. The upper end of this bracket is pivotally mounted upon a tubular extension 53 projecting from the frame and that tubular extension has rotatably mounted therein a shaft 5d which has fast thereto a gear 55 which meshes with the gear 5t. The shaft 54 extends into the base and is journalled ifi-suitable bearings therein and has fast thereto vis mounted in and carried by housing 59. The

housing is connected with a slide 60 which slides upon the way 43 and another way 6| on the upper side of the base I, Swivelly connected with the slide is a screw 62 which is rotatably mounted in a standard 63 supported from the baseand provided with a hand wheel 64 whereby when the screw is rotated the entire tail stock assembly may be moved to or from the head stock.

It should be explained at this point that the gearing heretofore described is so proportioned and synchronized that the workpiece is rotated one additional time upon its `own axis to the nnmber of times its axis moves in its circular path during the travel of the cutting tool one pitch distance of the threads of the workpiecewhich would result, due to the proportion and synchronization of the gearing, that during the travel of the cutting tool throughone pitch distance the workpiece has been brought into effective cutting relation with the ,cutter on a helical line which extends but once about the workpiece. This in eiect means that the workpiece has been rotated but one complete revolution with relation to the cutting tool during the travel of thetool one pitch distance of the threads of the workpiece.

` For instance, in a workpiece of a certain size,

i 961 revolutions will be imparted to the workpiece upon its own axis to 960 revolutions of the axis of the workpiece in its circular path during thecutting of one pitch distance. This results in a series of successive slightly spiral cuts being imparted to the workpiece, each cut beginning at a point slightly in advance of the preceding cut. Each cut starts slightly over the crown of the threads and grows deeper as the `axis of the workpiece moves toward the tool in its circular path to the full depth of the threads and then grows shallower as the axis of the workpiece moves away from the tool in its circular path until it reaches approximately its starting point.

When it isfdesired to turn a workpiece of a different size from that previously operated upon by the machine, after the tail stock has been properly adjusted with relation to the head stock to receive the mandrels it will also benecessary to change the disk 6 of each stock carrying the eccentric` points so as to give a greater or less movement to the axis of the workpiece in a circular path according to the size of the workpiece. It will also be necessary to change the gear 45 which drives the lead screw 44 in order to vary the extent of travel of the carriage 42 which supports the cutting tool, it being understood that the gearing which drives this leadl screw is so proportioned that a predetermined movement will be imparted to the tool for a certain number of predetermined rotations of the workpiece not only upon its own axis but also in a circular path.

Having thus'deso'ribed my invention, `I claim:

l. In a machine for forming a workpiece with y spiral threads, said machine having a head stock and a tail stock, a mandrel for each stock to support the .workpiece to rotate therewith, a disk associated with eachstock having an ecm centric centering pin to receive the corresponding mandrel, means for rotating said disk, a universal device `for each stock consisting of a rotatable member and a `block slidably mounted in said rotatable member, means `for rotating said rotatable member comprising a slidable connection between said means and said rotatable` member, eccentric means on said centering pin carrying disk to impart movement to said block yin said disk, means for connecting the corresponding mandrel with said block, and a cutter having a uniform feeding movement parallel with the axis of rotation of said workpiece.

2. In a machine for forming a workpiece with spiral threads, said machine having a head stock and a `tail stock and a mandrel forr each stock to support the workpiece to rotate therewith, a disk associated with each stock having an eccentric .centering pin to receive the corresponding mandrel, means torotate said disk, an eccentrically positioned flange on said disk, universal devices associated with each stock consisting of a ring and a block slidably mounted in said ring,

meansv to connect the corresponding mandrel 

